Hey, so yea, as @jonnotie said, and is described in detail in the Medium post, I was just so annoyed by the tiny grey Hangouts windows popping up all over my screen that I decided to write few lines of CSS overrides and published it as a Chrome extension...
Non-english language support is a bit meh and this version doesn't support notifications yet...
If you find any bugs would be cool if you submit them directly via web store http://bit.ly/1CGMYyf or email me to my firstname at lastname dot com or tweet me @airpoint
Cheers!

It's amazing how much you managed to improve Hangouts. The main problem with Hangout is like you said the fact that it doesn't have a native app. I think calls should have at least that or preferably even OS level integration. This is why Hangouts works so well for people with Android phones (and FaceTime for people on iOS/OS X).

This is great. I've always been very disappointed in the whole Hangouts experience, being on the phone, through the Chrome extension or directly in Gmail or Inbox. Inbox was the best so far when it came to how the chat windows looked like, but this is definitely going to replace it. Thanks!